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🔗 Russia 🔗 Mathematics 🔗 Statistics 🔗 Russia/science and education in Russia

In statistics, the Gauss–Markov theorem states that the ordinary least squares (OLS) estimator has the lowest sampling variance within the class of linear unbiased estimators, if the errors in the linear regression model are uncorrelated, have equal variances and expectation value of zero. The errors do not need to be normal, nor do they need to be independent and identically distributed (only uncorrelated with mean zero and homoscedastic with finite variance). The requirement that the estimator be unbiased cannot be dropped, since biased estimators exist with lower variance. See, for example, the James–Stein estimator (which also drops linearity) or ridge regression.

The theorem was named after Carl Friedrich Gauss and Andrey Markov, although Gauss' work significantly predates Markov's. But while Gauss derived the result under the assumption of independence and normality, Markov reduced the assumptions to the form stated above. A further generalization to non-spherical errors was given by Alexander Aitken.

🔗 United States 🔗 International relations 🔗 Soviet Union 🔗 Russia 🔗 Politics 🔗 Media 🔗 Journalism

Whataboutism, also known as whataboutery, is a variant of the tu quoque logical fallacy that attempts to discredit an opponent's position by charging them with hypocrisy without directly refuting or disproving their argument. It is particularly associated with Soviet and Russian propaganda. When criticisms were leveled at the Soviet Union during the Cold War, the Soviet response would often be "What about..." followed by an event in the Western world. As Garry Kasparov noted, it is a word that was coined to describe the frequent use of a rhetorical diversion by Soviet apologists and dictators, who would counter charges of their oppression, "massacres, gulags, and forced deportations" by invoking American slavery, racism, lynchings, etc. It has been adopted by other politicians and countries.

🔗 Soviet Union 🔗 Russia 🔗 Russia/technology and engineering in Russia 🔗 Spaceflight 🔗 Russia/science and education in Russia 🔗 Russia/history of Russia

Sputnik 1 ( or ; "Satellite-1", or "PS-1", Простейший Спутник-1 or Prosteyshiy Sputnik-1, "Elementary Satellite 1") was the first artificial Earth satellite. The Soviet Union launched it into an elliptical low Earth orbit on 4 October 1957, orbiting for three weeks before its batteries died, then silently for two more months before falling back into the atmosphere. It was a 58 cm (23 in) diameter polished metal sphere, with four external radio antennas to broadcast radio pulses. Its radio signal was easily detectable by radio amateurs, and the 65° inclination and duration of its orbit made its flight path cover virtually the entire inhabited Earth. The satellite's unanticipated success precipitated the American Sputnik crisis and triggered the Space Race, a part of the Cold War. The launch was the beginning of a new era of political, military, technological, and scientific developments. The name "Sputnik" is Russian for spouse/traveling companion or satellite when interpreted in an astronomical context.

Tracking and studying Sputnik 1 from Earth provided scientists with valuable information. The density of the upper atmosphere could be deduced from its drag on the orbit, and the propagation of its radio signals gave data about the ionosphere.

Sputnik 1 was launched during the International Geophysical Year from Site No.1/5, at the 5th Tyuratam range, in Kazakh SSR (now known as the Baikonur Cosmodrome). The satellite travelled at about 29,000 kilometres per hour (18,000 mph; 8,100 m/s), taking 96.2 minutes to complete each orbit. It transmitted on 20.005 and 40.002 MHz, which were monitored by radio operators throughout the world. The signals continued for 21 days until the transmitter batteries ran out on 26 October 1957. Sputnik burned up on 4 January 1958 while reentering Earth's atmosphere, after three months, 1440 completed orbits of the Earth, and a distance travelled of about 70 million km (43 million mi).

🔗 Russia 🔗 Russia/mass media in Russia 🔗 Central Asia 🔗 Insects 🔗 Ukraine 🔗 Russia/physical geography of Russia 🔗 Russia/history of Russia 🔗 Belarus

Depopulation of cockroaches in post-Soviet states refers to observations that there has been a rapid disappearance of various types of cockroaches since the beginning of the 21st century in Russia and other countries of the former USSR. Various factors have been suggested as causes of the depopulation.

🔗 Russia 🔗 Russia/technology and engineering in Russia 🔗 Physics 🔗 Physics/relativity 🔗 Russia/science and education in Russia

Cherenkov radiation (; Russian: Эффект Вавилова — Черенкова, Vavilov-Cherenkov effect) is electromagnetic radiation emitted when a charged particle (such as an electron) passes through a dielectric medium at a speed greater than the phase velocity (speed of propagation of a wavefront in a medium) of light in that medium. A classic example of Cherenkov radiation is the characteristic blue glow of an underwater nuclear reactor. Its cause is similar to the cause of a sonic boom, the sharp sound heard when faster-than-sound movement occurs. The phenomenon is named after Soviet physicist Pavel Cherenkov.

🔗 Aviation 🔗 Soviet Union 🔗 Russia 🔗 Russia/technology and engineering in Russia 🔗 Military history 🔗 Military history/Military aviation 🔗 Aviation/aircraft 🔗 Military history/World War II 🔗 Military history/Cold War 🔗 Russia/Russian, Soviet, and CIS military history 🔗 Military history/Russian, Soviet and CIS military history 🔗 Aviation/Soviet aviation

The Tupolev Tu-4 (Russian: Туполев Ту-4; NATO reporting name: Bull) is a piston-engined Soviet strategic bomber that served the Soviet Air Force from the late 1940s to the mid-1960s. The aircraft was a copy of the American Boeing B-29 Superfortress, having been reverse-engineered from seized aircraft that had made emergency landings in the USSR.

🔗 Russia 🔗 Russia/demographics and ethnography of Russia 🔗 Russia/history of Russia

The Russian Cross is the name of a demographic trend that occurred in Russia and many other countries of the former Warsaw Pact. In Russia, starting in 1988, birth rates among native Russians (as well as most other ethnic groups of the European part of the former Soviet Union) were declining, while from 1991 the death rates started climbing.

In 1992, the number of deaths exceeded the number of births, and continued to do so to a greater or lesser degree until 2013. When this trend is plotted on a line graph starting from the mid-1980s, the lines cross at 1992, hence the name.

🔗 Russia 🔗 Physics 🔗 Physics/relativity 🔗 Russia/science and education in Russia

The Novikov self-consistency principle, also known as the Novikov self-consistency conjecture and Larry Niven's law of conservation of history, is a principle developed by Russian physicist Igor Dmitriyevich Novikov in the mid-1980s. Novikov intended it to solve the problem of paradoxes in time travel, which is theoretically permitted in certain solutions of general relativity that contain what are known as closed timelike curves. The principle asserts that if an event exists that would cause a paradox or any "change" to the past whatsoever, then the probability of that event is zero. It would thus be impossible to create time paradoxes.

🔗 Soviet Union 🔗 Russia 🔗 Disaster management 🔗 Skepticism 🔗 Astronomy 🔗 Russia/science and education in Russia 🔗 Geology 🔗 Russia/physical geography of Russia 🔗 Russia/history of Russia 🔗 Paranormal

The Tunguska event was a massive ~12 megaton explosion that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate (now Krasnoyarsk Krai), Russia, on the morning of June 30, 1908. The explosion over the sparsely populated Eastern Siberian Taiga flattened an estimated 80 million trees over an area of 2,150 km² (830 sq mi) of forest, and eyewitness reports suggest that at least three people may have died in the event. The explosion is generally attributed to the air burst of a stony meteoroid about 50–60 metres (160–200 feet) in size.^{: p. 178} The meteoroid approached from the east-southeast, and likely with a relatively high speed of about 27 km/s. It is classified as an impact event, even though no impact crater has been found; the object is thought to have disintegrated at an altitude of 5 to 10 kilometres (3 to 6 miles) rather than to have hit the surface of the Earth.

The Tunguska event is the largest impact event on Earth in recorded history, though much larger impacts have occurred in prehistoric times. An explosion of this magnitude would be capable of destroying a large metropolitan area. It has been mentioned numerous times in popular culture, and has also inspired real-world discussion of asteroid impact avoidance.

🔗 Espionage 🔗 Internet 🔗 Russia 🔗 Russia/mass media in Russia 🔗 Russia/Russian, Soviet, and CIS military history 🔗 Russia/politics and law of Russia

Russian web brigades, also called Russian trolls, Russian bots, or more recently Kremlin Bots (after the Kremlin in Moscow) / Kremlins (a pejorative allusion to Gremlin) are state-sponsored anonymous Internet political commentators and trolls linked to the Government of Russia. Participants report that they are organized into teams and groups of commentators that participate in Russian and international political blogs and Internet forums using sockpuppets, social bots and large-scale orchestrated trolling and disinformation campaigns to promote pro-Putin and pro-Russian propaganda. Articles on the Russian Wikipedia concerning the MH17 crash and the 2014 Ukraine conflict were targeted by Russian internet propaganda outlets.